Continuous catalysis production method of PBT resin

Abstract

The invention discloses a continuous catalysis production method of PBT resin, and pulping, esterification, pre-polycondensation and polycondensation are carried out in order. The invention is characterized in that a catalyst conversion step is carried out before the pulping step, that is a compound with a structural formula Ti(OR)4 and 1, 4-butylene glycol are mixed and added into a catalyst preparation pot, in a condition with absolute pressure of 1-95kPa and temperature of 60-210 DEG C, a reaction is carried out for 0.5-10 hours, by-products ROH are removed, and a catalyst is obtained for a catalysis esterification reaction. According to the invention, a reaction between traditional Ti(OR)4 alkoxy titanium catalyst and 1,4-butylene glycol is carried out, a continuous reaction of PBT resin with a dihydric alcohol titanium catalyst is carried out, and at least one of alkoxys of the dihydric alcohol titanium catalyst is replaced by 1,4-butylene glycol. Hydrolysis resistance of the catalyst is good and catalysis effectiveness of the catalyst is guaranteed, simultaneously partial alkyl alcohols are recycled, and thereby reducing accumulation of alkyl alcohols in subsequent reactors, reducing influences on esterification reaction and dehydration process, reducing alkyl alcohols in waste water, and reducing COD of waste water.

Description

technical field [0001] The invention relates to a preparation method of PBT resin, in particular to a continuous catalytic production method of PBT resin, belonging to the technical field of PBT synthesis. Background technique [0002] Catalysts play a vital role in the production of polybutylene terephthalate (PBT). At present, the esterification step and polycondensation step in the PBT process route at home and abroad generally use alkoxy titanium catalysts, such as tetrabutyl titanate, tetraisopropyl titanate, etc. Although tetrabutyl titanate has a high catalytic activity, there are still the following deficiencies in the actual production process: ① by-product alkyl alcohol, such as butanol produced by the catalysis of tetrabutyl titanate, will accumulate in the reaction tower , affect the normal operation of the reaction tower; ②The discharge of alkyl alcohol from the wastewater will increase the burden of wastewater treatment; ③The alkoxide titanium catalyst is easy...

AI Technical Summary

Problems solved by technology

Although tetrabutyl titanate has a high catalytic activity, there are still the following deficiencies in the actual production process: ① by-product alkyl alcohol, such as butanol produced by the catalysis of tetrabutyl titanate, will accumulate in the reaction tower , affect the normal operation of the reaction tower; ②The discharge of alkyl alcohol from the wastewater will increase the burden of wastewater treatment; ③The alkoxide titanium catalyst is easy to hydrolyze, and the water generated in the esterification step will accelerate the hydrolysis, and the generated hydrolysis product titanium dioxide not only It is easy to accumulate on the wall of the reactor, which will affect the heat transfer and affect the quality of subsequent products

It has been reported in the literature that the use of nano-titanium dioxide as a catalyst can inhibit the hydrolysis of the catalyst while maintaining high catalytic activity, but the post-treatment is complicated and not suitable for industrial production

There are also reports in the literature that complexation methods are used to prepare hydrolysis-resistant catalysts, but the addition of complexing agents not only increases the cost of the product, but also may affect the reaction process and the application of subsequent products.

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